1. Field of the Invention
The present invention relates to an information distribution system such as a video-on-demand (VOD) system. More particularly, the present invention relates to a method and apparatus for processing content and other assets such that the other assets may be injected into a subsequent content stream.
2. Description of the Background Art
Information distribution systems, such as video on demand (VOD) system providing content encoded according to the various Moving Pictures Experts Group (MPEG) standards are known. For example, a first standard known as MPEG-1 refers to ISO/IEC standards 11172, which is incorporated herein by reference in its entirety. A second standard known as MPEG-2 refers to ISO/IEC standards 13818, which is incorporated herein by reference in its entirety. Additionally, a compressed digital video system is described in the Advanced Television Systems Committee (ATSC) digital television standard document A/53, incorporated herein by reference.
An interactive information distribution system provided by DIVA Systems Corporation of Redwood City, Calif. is described in more detail in U.S. Pat. No. 6,253,375, which is incorporated herein by reference in its entirety. Users or subscribers to the DIVA system select information offerings using a “Navigator” functionality, which is described in more detail in U.S. Pat. No. 6,253,375 and incorporated herein by reference in its entirety. Briefly, the Navigator utilizes a combination of MPEG content (such as MPEG video content and related MPEG audio content) and Navigator asset data to provide viewers with a means of selecting and ordering services. Navigator assets include bitmaps and navigation control scripts. As the set top box user is “navigating,” the set top box extracts the asset data from the transport stream and uses that data to provide bitmap overlays on top of the MPEG content. The control data within the assets is used to define the layout of the screen and to take actions based on viewer input.
Assets, such as the aforementioned Navigator assets, are typically packaged as MPEG transport packets that are multiplexed along with content-representative MPEG packets to produce a single MPEG transport stream file. The file is then transported to and stored on each of, possibly, many servers for subsequent transmission to the users' set top boxes.
Unfortunately, embedding assets such as Navigation assets within the content places a severe limitation on changes to the assets. For example, if a bitmap asset must be changed to provide new graphic data, the content files for all navigation screens using that bitmap need to be re-multiplexed, redistributed, and re-loaded onto all servers. Additionally, the multiplexing of the Navigation assets and content results in a duplication of the Navigation asset data within each of a plurality of content streams including the data.
Therefore, it is seen to be desirable to provide a method and apparatus for inserting assets, such as navigation assets, into a content stream in a manner avoiding the above-described problems.